One of the most important sets of instructions that seem to be forgotten by everyone is how to READ their tank labels. Without knowing how to read the label, you can't find tank sizes, hydrotest dates, manufacturers, or if the tank is even legal to use in the country you play paintball in.

PLEASE bear in mind that not all labels are the same. Some only have minimum information required, while others have everything under the sun. MOST labels have a similar layout, though there is no requirement for this.

Here's my test labels:

AS you can see, it's from a NitroDuck tank, and I have most of the information on it highlighted in various colors. The Carleton tank on the right does not, mainly due to layout. MOST labels are very similar in layout, but with varying amounts of information.

From the top down, here's what on this label:

Light Blue: Transport Canada Permit Number. This is REQUIRED to be Current in order to be usable in Canada. Your Hydrotest period is determined by this number. Look up the permit number for current information.

Dark Blue: USDOT Exemption Number. This is REQUIRED to be current in order to be usable in the USA. Many of these numbers are no longer being renewed by the USDOT, and are no longer usable. Your Hydrotest period is determined by this number. Look up the exemption number for current information.

Exemption Numbers are not shared. ALL tanks made with a specific number are manufactured by the same company. That same company may have MANY different exemption numbers assigned to it for different types of tanks though.

Pink: Pressure Rating. On the top line with the Canadian permit number is the metric rating - 310 Bars. The second line with the US Exemption Number is the US standard rating - 4500 PSI.

Red: Serial Number. The prefix of the serial number shown , in this case FW, changes for every company that uses these bottles in a finished product. Some recalls are based of a range of these numbers with a specific prefix.

White: Tank Manufacturer. In this case, Luxfer.

Yellow: Tank Hydrotest Date / Born On Date - your tank's retest date is found by adding years to this date. In this picture the date is April / 04, and the retest would be due by April 1, 2009, based on the exemption number information. The symbol in the date will change depending on the certifying authority, but most commonly will be an "Arrow-A", or a "CL"

Green: Tank Part/Model Number. The part number/model number is used to determine the tank specifications based on the manufacturer's information. This will generally include: Volume, Dimensions, Weight, Material, Exemption Number. Some Companies sell tanks listed as a different size than the manufacturer to make them more appealing and raise the price. Just to the right of this is the material, which is Carbon Fiber in this case.

Not highlighted: REE - Rejection Elastic Expansion. This is the permanent volumetric expansion at which the tank is decertified for use. It means the tank has stretched beyond the safe limits of its specifications.

The main differences on the Carleton label is the Model Number, Serial Number, and the "M4927" number in the top right corner. On this label, the Model Number and Serial Number are combined into this: 6151-101630... 6151 is the model number, while 101630 is the serial number. M4927 is the USDOT assigned manufacturer's number for Carleton.

IMPORTANT!! Some tank labels, such as the Carleton example above, may say Retest every ## years per US DOT or TC-SU.
That information may be inaccurate!! LOOK UP THE EXEMPTION NUMBER!! The retest period CAN CHANGE. Even though the label says one thing, your tank may qualify under more current rulings for a different test period.

LUXFER EXAMPLES:
(No Model Number, No Material Listing)

(4500 PSI Overfill warning added, 68 Cu added)

(No Transport Canada Permit Number, NOT LEGAL IN CANADA)

CARLETON EXAMPLES:

(HSE-AL-FW2 is UK Certification, PH466 Bar is test pressure)

INOCOM EXAMPLES:
(06IDC054 is the Serial Number, P110C02-01 is the Model Number, PBC00074 is the series number, M-0503 is the manufacturer number)

The following information applies to ALL Aluminum Compressed Air tanks and Aluminum CO2 Tanks

All aluminum tanks (whether compressed air or CO2) will have this information STAMPED into the tank, not necessarily printed on a label. THe Stamps may
be hard to find, but they ARE there. For the purpose of this thread, I have taken white paint and filled in the stamping so that the (otherwise impossible to see) information is visible for my camera.

These images were taken sequential so that you could see how the stamping is generally placed on Aluminum tanks (common on 48-3000, 72-3000, 9oz, 12oz, 20oz, 24oz tanks)

AS you can see, I've highlighted sections of the tank information, just as I did on the composite tanks above.

The same color in all 3 photos will highlight the same information.

RED: DOT-3AL stamp - Designates the tank as ALUMINUM. NOT STEEL

GREEN: 1800 - This is the WORKING PRESSURE. This is the maximum rated operational pressure of the tank. The hydrotest pressure is x5/3 (2 1/3) this pressure. Just because the test pressure is that high, does NOT make it safe to fill the tank above this (in the case of HPA tanks!)

AQUA: Manufacturer's Serial number

YELLOW: Manufacturer's Symbol (Number) - ALL tank manufacturers, (whether making aluminum, steel, composite, etc.) are assigned a manufacturer's Symbol or ID number. THe number will range from M1000-M5999. ALways starts with M, and is always 4 digits. This number can be referenced here: DOT Manufacturer Symbols to find out who REALLY made that tank you're carrying. This number is also present on some composite HPA tanks.

BLUE: Hydro Date - This is the BORN ON date of your tank; when it was manufactured. ALL "3AL" ALUMINUM TANKS ARE 5 YEAR TEST CYCLES. (Yes, there is the exception, but that will be covered at the end)

PINK CIRCLE: Manufacturer's Stamp: Not every tank will have this. Some companies put a trademark stamp on their tanks as well.

MAGENTA: Tare Weight/Volume of tank: On CO2 tanks, this will have the CO2 weight that can be put into the tank. for HPA bottle, this will have the cubic inch capacity of the tank.

WHITE: TC-SU Stamp - This is the TRansport Canada number that says this tank is authorized for use in Canada. I believe that Aluminum tanks are also 5 year test cycles in Canada as well.

Now for some thoroughly confusing information.

This is a 3.5oz ALuminum CO2 tank. Notice how the information on the tank is DIFFERENT? The reason for that is because this tank is exempt from hydrotesting rules.

BLUE: DOT Special Permit Number 7737 - This permit number designates a 3E hydrotesting exempt tank. (this is a rarity, as the general rule of thumb is that 3E tanks must be made from chrome-moly steel. This is an aluminum tank, however) IF your tank is metal, and DOES NOT have "3AL" or "3HT" stamped on it, PLEASE look up the special permit online to check the restrictions/ conditions of use of your tank. IF your special permit is NOT listed in the USDOT PHMSA website, then it has expired, and your tank is NO LONGER VALID FOR USE.

MAGENTA: 1800 - This is the WORKING PRESSURE. This is the maximum rated operational pressure of the tank. The hydrotest pressure is x5/3 (2 1/3) this pressure. Just because the test pressure is that high, does NOT make it safe to fill the tank above this (in the case of HPA tanks!)

YELLOW: Hydro Date - This is the BORN ON date of your tank; when it was manufactured. This tank is one of those exceptions to the 5 year test rule - it does not need to be tested, ever.

AQUA: TC-SU Stamp - This is the TRansport Canada number that says this tank is authorized for use in Canada.

You may notice this tank also says "ALUMINUM ALLOY" on it. This is a requirement of the special permit, being an aluminum tank classified under 3E regulations.

Now for another oddity in CO2 tanks - Chrome-Moly Steel...

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BLUE: DOT Special Permit Number 8096 - This permit number designates a 3E hydrotesting exempt tank manufactured from CHrome-moly steel. This special permit number is no longer available from the USDOT PHMSA for reference because it is expired, making it illegal to service this tank.

MAGENTA: 1800 - This is the WORKING PRESSURE. This is the maximum rated operational pressure of the tank. The hydrotest pressure is x5/3 (2 1/3) this pressure. Just because the test pressure is that high, does NOT make it safe to fill the tank above this (in the case of HPA tanks!)

YELLOW: Hydro Date - This is the BORN ON date of your tank; when it was manufactured. This tank is one of those exceptions to the 5 year test rule - it never needed testing.

Hydrotesting information

On to some wonderful additions to the hydrotesting rules. AS you can see, I have some 3E-hydrotest exempt tanks shown. Here's the special info about these tanks: ALL 3E tanks must be Chrome-MOLY steel UNLESS specified as such by the special permit issued by the USDOT PHMSA. This does NOT mean that all chrome-moly tanks are 3E-hydrotest exempt.

For METAL tanks, hydro test dates must be STAMPED into the tank to be valid. If the hydrotest information is put on a sticky label of any kind for a metal tank, it is NOT a valid recertification. The ONLY exception is for Fire Extinguisher tanks; meaning designed and USED as a fire extinguisher.

Prior Retest dates ARE NOT legal to remove unless all of the following conditions are met:
1: There is no further room for retest dates to be added:
2: The original manufacturing test date is not removed.
3: The owner's permission is obtained FIRST.
4: Minimum sidewall thickness is maintained (for metal cylinders)

The re-test date cannot be stamped into the sidewall of the tank, unless permitted by the ORIGINAL tank specification. 3E cylinders do allow for this.

The wonderful -2"x2'- rule: Any cylinder not exceeding 2 inches outside diameter and less than 2 feet in length is excepted from volumetric expansion test. NOTE: 49 CFR 180.209 does not say ONLY tanks adhering to this rule are exempt. It says tanks that meet the 2 x 2 rule are INCLUDED in the exemption from requiring retest. 3E tanks commonly exceed these dimensions.

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Now, this information mainly covers 3AL type aluminum tanks, and 3E Chrome-Moly steel tanks. There is another metal tank still found in use. These tanks have a "3HT" stamped on them. These chrome-moly steel tanks ARE NOT FOR USE IN PAINTBALL. They are ONLY certified for AVIATION USE. They were sold mainly by Crossfire quite a few years ago.
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INFORMATION LINKS:Special Permits Index - Look up your tank's exemption number, print it out, and keep it with your gear. These are updated frequently, and will TELL YOU HOW OFTEN YOUR TANK MUST BE RETESTED. PLEASE READ. They will also tell you WHO actually manufactured the tank.

Transport Canada's TDG Permit list - Same list as above, but for TC-SU Canadian stamps. If your tank doesn't have a TC-SU number, it CANNOT be used in Canada. Period. (The USDOT PHMSA does recognize TC-SU stamps and testing)

Authorized Cylinder Retesters List - Find a LOCAL hydrotester; it's always an option. Maybe save some shipping time and not worry about the USPS losing your $200+ tank. Hydrotesters MUST have HIGH PRESSURE or INDUSTRIAL (HIGH AND LOW PRESSURE) listed beside their name in order to be used. Low pressure or visual inspections only DO NOT QUALIFY.